It's always imortant to realize that black slaveowners and black confederates were a very tiny percentage of the whole, and were, by an extreme amount, the exception.
There is nothing even close to a justification for slavery. Period.
I know you weren't trying to justify slavery, but I think it's very important, given the terrible history of the institution that we don't forget the true nature of the system. I think it is right that when we look at slavery, we see the negative aspects, because even many of the things we call positives were only lighter negatives.
btw, as to the numbers of blacks in the Confederacy, a couple of questions. 1, wouldn't it have been very late in the war before blacks were allowed to fight in most places, given the Southern attitudes toward black soldiers and the reaction to Cleburne's proposal? 2. I'm curious as to the source for the numbers, since they seem high in light of the estimate I've seen that there were 900,000 confederate soldiers overall, and no black Confederate soldiers were ever taken prisoner by the North.
I know McPherson and others doubt some of the reports of a large number of black Confederates, though there were obviously some. I think there's overall some objection to classifying those who accompanied the armys as servants--including those who carried arms for their masters, but who did not take part in battles--as soldiers.